Antenna



March 24, 1953 RABURN 2,632,848

. ANTENNA Filed Dec. 3, 1948 v 11 n u I 1 zwl/z'xzrzzazu ra [3/ 1212M il lnderwq (,UMIM, M w-LJM ATTORNEY is described specifically herein.

Patented Mar. 24, 1953 son, Evansville, Ind., assignors to Electronics Research, Inc., Evansville, Ind., a corporation of Indiana Application December a, iciaseriai Nb. 63,366

8 Claims. 1

' This invention relates to an improved antenna for mounting on a structure having a conducting outer surface, and especially on vehicles havinga' conducting skin, such as motor busses. aircraft, and the like. It is an object of the invention to provide an antennafor. such uses in which the conducting surface constitutes a ground plane and forms an integral part of the antenna, the radiation pattern being reasonably circular.

In its preferred form the, antenna of the invention is formed of metal and is devoid of insulators. Thus the structure is extremely rugged and is capable of withstanding the shocks normally incident to the intended use. At the same time the structure is simple and inexpensive,

neat in appearance, and inconspicuous.

. More specificallyflt is an object of the invention to provide an antenna for vehicular use which comprises a pair of substantially aligned radiating elements, disposed parallel to the vehiole skin, and mounted thereon by relatively short conducting legs.

Further objects and features of the invention will be apparent'from the following description and the accompanying drawings, in which Fig. 1 'is a plan view of antenna constructed in accordance with the invention, showing the same mounted on the-forward end of a motor bus.

Fig. 2 is a front elevation of the structure shown in Fig, 1,;

Fig. 3 is a partial section taken on the. line .3'-.-3 of Fig. 2;

Fig. i is a section on the line 44 of Fig. 3;

and V Fig; 5 isa section on the line 5-5 of Fig. 3. Tofacilitate. an. understanding of the invention, the embodiment illustrated in the drawing It will nevertheless be understood that no limitation of the invention is thereby intended, such further modifications and alterations being'contempla'ted as would normally occur to those skilled in the art to which the invention relates.

Referring first to Figs. 1 and 2, the antenna is shown in assembled relation on the front end of a bus ill, above the windshield II, and below the usual route sign i2. This location is selected largely for convenience, since the antenna may be located on any conducting surface.

The antenna comprises'ap'air of elongated radiating elements i5 which aredisposed subf stantially in alignment with each other and in parallelism with the metal skin of the vehicle.

Elements I5 may be constituted by metal tubes,

(01. ssu -es) each tube being bent inwardly at its outer end toward the vehicle body to provide a leg IS, the legs being flattened as indicated at i! and there bolted or otherwise secured to the vehicle skin. At their adjacent ends, elements it: are connected to the vehicle skin by adjacent legs is, the legs serving as feeder sections for the radiating elements 15, as hereinafter more fully explained.

It will thus be observed that the antenna may 7 be described as comprising two generally U- shaped portions defining a common plane inter secting the conducting vehicle skin, the legs of each U portion being short and being conductively secured to the metal skin. The signal to be radiated is fed to the adjacent legs 18 by a coaxial transmission line 20, the outer and inner conductors being connected respectively to the legs 18 at I9 and H.

As shown more particularly in Figs. 3-5 inclusive, legs or feeder sections i8 may constitute part of an integral U-shaped. bracket of which the base 2c is bolted or otherwise secured as shown at 25 to the vehicle skin it. Formed on each of the legs it of this bracket is a stud dimensioned for reception in the adjacent end of av tubular radiating element 15, the parts being held in assembled relation by bolts 21. To improve the appearance. of the device and to exclude dustfrom the several connections, the bracket is provided. with a coverzs of plastic or other suitable non-conducting material.

It will be noted that the outer conductor of the transmission line is grounded on the vehicle skin by connection to the base 24 of the casting intermediate the adjacent legs or feeder sections it of the antenna, as indicated at 30.. Thisallows the impedance of the coaxial line with. respect 7 to ground to increase with that of the feeder section, thus establishing a balanced condition. The

antenna is so dimensioned that the length of. the

supporting legs it, 18, is lessthan and preferably only a small part of a quarter wavelength ,of

the signal to be radiated, while the length of each radiating element I5 is greater than a quarter wave length and is preferably approximately onehalf wave length. In operation the adjustment should be such that at the transmitted frequency the inductive reactance of the legs or feeder sections will be equal to the capacitive reactance of theradiating elements l5. Where it is not possible to establish optimum operating con-V. ditions, for instance because of lack of space,

shorter radiating elements l5 may be employed and suitable adjustment effected by a loading condenser 35, connected across the legs i8 as 1. Anantenna for mounting on a vehicle having a conducting outer surface, comprising a pair of substantially aligned elongated radiating elements disposed generally parallel to said surface, and spaced in the direction of their length, each of said elements being provided at each of the opposite ends with a conducting leg extending,

toward and conductively secured to said surface, and a transmission feed line connected to the two adjacent legs on the said elements.

2. An antenna for mounting on a vehicle having a conducting outer surface, comprising a pair of substantially aligned elongated radiating elements disposed generally parallel to said surface, each of said elements being provided at each of the opposite ends with a conducting leg extending toward and conductively secured to said sur- 1 1 face, and a transmission feed line connected to the two adjacent legs on said elements, said radiating elements having a length greater than one fourth, and said legs having a length substantially less than one fourth, the wave length of the signal to be radiated.

3. An antenna as claimed in claim 2 in which the radiating elements have a length substantially one-half of the wave length of the signal to be radiated.

4. An antenna for mounting on a vehicle having a conducting outer surface comprising a pair of substantially aligned elongated radiating elements disposed generally parallel to said surface, and spaced in the direction of their length, said elements being provided at the ends thereof with conducting legs extending toward and secured to said surface, and a transmission feed line connected to the two adjacent legs on the said elements, the lengths of the said elements and the said legs being such that the capacitive reactance of said elements is substantially equal to the inductive reactance of said legs.

5. An antenna for mounting on a vehicle having a conducting outer surface comprising a pair of substantially aligned elongated radiating elements disposed generally parallel to said surface,

each of said elements being provided at each of the opposite ends with a conducting leg extending toward and conductively secured to said surface, a transmission feed line connected to the two adjacent legs on the said elements, and a variable loading condenser connected across said adjacent legs.

6. An antenna for mounting on a vehicle having a conducting outer surface, comprising a pair of substantially aligned elongated radiating elements disposed generally parallel to said surface, and spaced in the direction of their length, each of said elements being provided at each of the opposite ends with a conducting leg extending toward and conductively secured to said surface, and a coaxial cable feeding said antenna the outer conductor of said cable being grounded to said skin intermediate the adjacent pair of legs and being connected to one of said adjacent legs, the inner conductor being connected to the other of said adjacent legs.

'7. An antenna for mounting on a vehicle having a conducting outer surface comprising a pair of substantially aligned elongated radiating elements disposed generally parallel to said surface, said elements being provided at the remote ends thereof with conducting legs extending toward and conductively secured to said surface, and a, generally U-shaped conducting bracket having a base conductively secured to said surface and having outwardly directed legs conductively secured respectively to the adjacent ends of said elements, and transmission line connections on said bracket.

8. An antenna for mounting on a vehicle having a conducting outer surface comprising a pair of substantially aligned elongated radiating elements disposed generally parallel to said surface, said elements being provided at the remote ends thereof with conducting legs extending toward and conductively secured to said surface, a generally U-shaped conducting bracket having a base conductively secured to said surface and having outwardly directed legs conductively secured respectively to the adjacent ends of said elements, and a coaxial cable having the inner and outer conductors thereof respectively connected to said last-named legs to feed said antenna, said outer conductor being grounded on said bracket base intermediate the bracket legs. LOUIS EARL RABURN.

RICHARD WARREN ANDERSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number OTHER REFERENCES Tele-tech, March 1947, page 58. Proceedings of IRE, January 1948, page 68. 

